//==============================================================================
//
//  This file is part of GPSTk, the GPS Toolkit.
//
//  The GPSTk is free software; you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as published
//  by the Free Software Foundation; either version 3.0 of the License, or
//  any later version.
//
//  The GPSTk is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with GPSTk; if not, write to the Free Software Foundation,
//  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110, USA
//  
//  This software was developed by Applied Research Laboratories at the
//  University of Texas at Austin.
//  Copyright 2004-2020, The Board of Regents of The University of Texas System
//
//==============================================================================

//==============================================================================
//
//  This software was developed by Applied Research Laboratories at the
//  University of Texas at Austin, under contract to an agency or agencies
//  within the U.S. Department of Defense. The U.S. Government retains all
//  rights to use, duplicate, distribute, disclose, or release this software.
//
//  Pursuant to DoD Directive 523024 
//
//  DISTRIBUTION STATEMENT A: This software has been approved for public 
//                            release, distribution is unlimited.
//
//==============================================================================

/**
 * @file LinearClockModel.hpp
 * This model is just a moving average of clock models over time. It
 * really is quite bad and shouldn't be used at this time. Be warned!
 */

#ifndef LINEARCLOCKMODEL_HPP
#define LINEARCLOCKMODEL_HPP
 
#include <map>

#include "Exception.hpp"

#include "ObsClockModel.hpp"
#include "ORDEpoch.hpp"



namespace gpstk
{
      /// @ingroup ClockModel
      //@{

   class LinearClockModel : public ObsClockModel
   {
   public:
      LinearClockModel(double sigma = 2, double elmask = 0, SvMode mode = ALWAYS)
            :ObsClockModel(sigma, elmask, mode) {reset();};

      virtual double getOffset(const gpstk::CommonTime& t) const 
         throw()
      {
         if (!isOffsetValid(t))
            return 0;
         else
            return clockModel.Slope()*(t-baseTime) + clockModel.Intercept();
      };

      virtual bool isOffsetValid(const gpstk::CommonTime& t) const throw()
      {return t >= startTime && t <= endTime && clockModel.N() > 1;};

         /** Add in the given ord to the clock model.
          * @throw InvalidValue
          */
      virtual void addEpoch(const ORDEpoch& oe);

         /// Reset the accumulated statistics on the clock
      void reset() throw();

      void dump(std::ostream& s, short detail=1) const throw();

      friend std::ostream& operator<<(std::ostream& s, const LinearClockModel& r)
      { r.dump(s, 0); return s; };
      
   private:
         // x is time y is clock offset
      gpstk::TwoSampleStats<double> clockModel;

      gpstk::CommonTime startTime, endTime, baseTime;

      unsigned long tossCount;
   
         // This is were we store what SVs were used to compute the individual
         // clock observations
      std::map<gpstk::CommonTime, SvStatusMap> prnStatus;

         // This is a store of the clock observations that were added into the
         // clockModel object
      std::multimap<double,double> clockObs;
   };

      //@}

}
#endif
